---
name: "2D_D"
section: "3rheolef"
platform: "linux"
package: "librheolef-dev"
version: "6.1-2.1"
release: "Debian 7 (Wheezy)"
platforms: ["linux"]
url: "https://new.carta.tech/2D_D"
---

# 2D\_D(3rheolef)

## NAME

**2D\_D** -- -div 2D operator

## SYNOPSIS

```
        form (const space V, const space& V, "2D_D");

```

## DESCRIPTION

Assembly the form associated to the **div(2D(.))** components of the operator on the finite element space **V**:

```
                 /
                 |
        a(u,v) = |  2 D(u) : D(v) dx
                 |
                 / Omega

```

where

```
                1 ( d ui   d uj )
      Dij(u) =  - ( ---- + ---- )
                2 ( d xj   d xi )

```

This form is usefull when considering elasticity or Stokes problems.

## EXAMPLE

Here is an example of the vector-valued form:

```
        geo omega ("square");
        space V (omega, "P2", "vector");
        form  a (V, V, "2D_D");

```

Note that a factor two is here applied to the form. This factor is commonly used in practice.